.css {
  .sample {
    width: 100px;
    border: 10px solid red;
    padding: 10px;
  }

  .sample1 {
    .sample();
    box-sizing: border-box;
  }

  .box {
    float: left;
    width: 100px;
    border: 1px solid red;
  }
  .box-clear {
    clear: both;
  }

  .clear-float {
    overflow: auto;
    .img-float {
      float: right;
    }
  }
}
